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Thread: Conical vs burr grinders - a sceptic no more

  1. #101
    Senior Member Gavisconi007's Avatar
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    Gobble-Dee-Gook at its finest......

  2. #102
    Senior Member gonzob's Avatar
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    Thanks, Yelta. It is very interesting. It doesn't answer the question. The word "conical" doesn't actually appear in the article.

    Skidquinn's observations are also interesting, in that he/she sees an obvious difference in the grind. But, we don't know why.

    Gonzo

  3. #103
    Senior Member Yelta's Avatar
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    Quote Originally Posted by gonzob View Post
    Thanks, Yelta. It is very interesting. It doesn't answer the question. The word "conical" doesn't actually appear in the article.

    Skidquinn's observations are also interesting, in that he/she sees an obvious difference in the grind. But, we don't know why.

    Gonzo
    There are many mysteries in life that remain unanswered Gonzo, Matt has provided a wealth of information, perhaps here is your opportunity to put your grey matter into action and come up with the definitive answer, having done that you may then care to explain to us, now that we are in possession of this knowledge, how exactly this is going to manifest itself into our overall enjoyment of our beverage of choice.

    On the other hand, you could just forget the whole meaningless exercise, probably the smartest option.
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  4. #104
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    Mystery? What mystery?

    Quote Originally Posted by samuellaw178 View Post
    The grind particles distribution are very different. ie. Grinding doesn't yield mono-sized grind particles, but a range of particles of different sizes. These distribution of grind sizes are different among different grinders.

    With such difference in grind size distribution , it'd be a mystery if flat tastes the same as conical....

    p/s: If you want the original image/resolution, you have to search for Socratic Coffee's Instagram (it's hidden somewhere in their archive). They've done some pretty impressive tests but may be over the top for some of us who just want a simple cup.
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  5. #105
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    Mystery? What mystery?
    With such difference in grind size distribution , it'd be a mystery if flat tastes the same as conical....
    And why every variation of grinder in between tastes different again!

    So once again we come to that same spot - let taste (and budget!) be your guide!
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  6. #106
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    Quote Originally Posted by Gavisconi007 View Post
    Gobble-Dee-Gook at its finest......
    Someone is actually doing proper scientific research and you mock it. Sad, very sad ...

  7. #107
    Senior Member Yelta's Avatar
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    Quote Originally Posted by dlight View Post
    Someone is actually doing proper scientific research and you mock it. Sad, very sad ...
    "Proper scientific research" Eh, as opposed to improper I guess.

    Gavisconi007 is pretty switched on re grinders and is a regular contributor, FWIW I reckon his assessment of the article was pretty well spot on "Gobble-Dee-Gook"
    Science.png
    Last edited by Yelta; 21st May 2016 at 10:13 AM.

  8. #108
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    Quote Originally Posted by Yelta View Post
    "Proper scientific research" Eh, as opposed to improper I guess.

    Gavisconi007 is pretty switched on re grinders and is a regular contributor, FWIW I reckon his assessment of the article was pretty well spot on "Gobble-Dee-Gook"
    Science.png
    In fairness, there is a lot of 'improper' scientific research out there - it usually doesn't get published or is published in a dodgy journal. The original article was published in Nature Scientific Reports, which is a well respected peer reviewed journal. This means that at least three scientists would have reviewed the manuscript before approving it for publication. Now I'll admit that none of those reviewers probably had coffee expertise, but would have been expert in the analysis techniques used and experimental design. While I don't see liquid nitrogen cooled, vacuum sealed grinders in our future it's still an interesting study - particularly for those in the area of food science.

  9. #109
    Senior Member Gavisconi007's Avatar
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    Case in point......"Heating the beans to achieve consistency pushes the beans above the shatter transition temperature and significantly reduces the total surface area (read: less and less-even extraction).More cold = finer particles = more surface area = higher extraction. Lower temperatures could also mean less evaporation/sublimation of aromatic compounds (aroma loss)."

  10. #110
    Senior Member Yelta's Avatar
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    Quote Originally Posted by DaveD View Post
    In fairness, there is a lot of 'improper' scientific research out there - it usually doesn't get published or is published in a dodgy journal. The original article was published in Nature Scientific Reports, which is a well respected peer reviewed journal. This means that at least three scientists would have reviewed the manuscript before approving it for publication. Now I'll admit that none of those reviewers probably had coffee expertise, but would have been expert in the analysis techniques used and experimental design. While I don't see liquid nitrogen cooled, vacuum sealed grinders in our future it's still an interesting study - particularly for those in the area of food science.
    Nature Scientific Reports is pretty much a newcomer on the scene and doesn't exactly have a stellar track record so far, do a bit of digging and comments such as this can be found.

    ""Why would you publish in Scientific Reports?" Because your paper was rejected by everything else? "

    "In 2015, an editor resigned from Scientific Reportswhen the journal introduced a trial of a fast-track peer-review service for biology manuscripts in exchange for an additional fee." [

    Not sure what any of this has to do with conical burr grinders, thought I had best chuck the term in as an afterthought, in an endeavour to remain on topic.
    Last edited by Yelta; 21st May 2016 at 11:24 AM.
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  11. #111
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    There are worse journals, and its impact factor is a bit over 5, which is not bad. A journal always had to start somewhere. Enough said on the topic though - back to conicals!
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  12. #112
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    There are a couple of rather questionable assumptions in that paper - not least of which is that particle surface area can be approximated as a sphere of equivalent diameter. Research investigating the surface area is easy to find, and indicates this is most certainly not the case.

    Grinders have been used for all kinds of applications for a long time (e.g. in mineral processing, pharmaceuticals, food production) - I'm sure there are some insights into the difference in grinder geometry in the engineering literature, if you know where to look.
    Last edited by MrJack; 21st May 2016 at 02:55 PM.

  13. #113
    Senior Member Yelta's Avatar
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    Mr Jack is correct, mineral processing and coffee grinding has much in common.

    The mining industry use a variety of crushers/pulverisers, jaw crushers, conical crushers, ball mills, pulverisers to name a few, I spent over 10 years working with this type of machinery in the far north of SA preparing ore samples for analysis, and am very familiar with its operation, the experience was invaluable and easily transferable to the process of grinding coffee.

    Here's a link to a commercial site depicting some of the machinery available, interesting to note they offer a coffee mill with a maximum output of 2500 KG per hour, wonder how you would go single dosing this one

    http://www.directindustry.com/prod/n...tm_campaign=CA
    Last edited by Yelta; 21st May 2016 at 01:27 PM.
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  14. #114
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    Quote Originally Posted by Yelta View Post
    Here's a link to a commercial site depicting some of the machinery available, interesting to note they offer a coffee mill with a maximum output of 2500 KG per hour, wonder how you would go single dosing this one

    http://www.directindustry.com/prod/n...tm_campaign=CA
    You'd have to "season" it with a few tonnes of rice first
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  15. #115
    Senior Member magnafunk's Avatar
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    Any sponsors looking at carrying this grinder? Would look good poking out the back of my house
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  16. #116
    Senior Member readeral's Avatar
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    Retention is a bit of a problem...

  17. #117
    Senior Member Yelta's Avatar
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    Quote Originally Posted by readeral View Post
    Retention is a bit of a problem...
    Retention/contamination is certainly undesirable in the sample prep process, clean up involving brushing, vacuuming and at times processing a batch of barren quartz between samples is necessary.

    As I said similarities.

  18. #118
    Senior Member readeral's Avatar
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    Quote Originally Posted by Yelta View Post
    Retention/contamination is certainly undesirable in the sample prep process, clean up involving brushing, vacuuming and at times processing a batch of barren quartz between samples is necessary.

    As I said similarities.
    Serves me right for being facetious!

  19. #119
    Senior Member Yelta's Avatar
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    Quote Originally Posted by readeral View Post
    Serves me right for being facetious!
    Not at all, how would you know?

    As I commented earlier, the processes are very similar.

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    Quote Originally Posted by Yelta View Post
    Not at all, how would you know?

    As I commented earlier, the processes are very similar.
    Subtle.

    Perhaps mineral processing wasn't the most directly applicable example

    The point was simply that the principles of grinding are not necessarily unique to coffee.

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    As a home user I have been interested in getting a conical grinder. I currently use a Macap 4MD. I make 1-3 double shots per day. The main thing that puts me off is the retained grounds. I know a lot of the large conicals contain about 20-50 g of retained grounds. So I am faced with an option of substantial wastage of coffee or using stale stuff that has been sitting in the grinder. Does anyone know how much coffee is in the K10? Also any thoughts on the new Mahlkonig Peak?
    cNc

  22. #122
    Senior Member Gavisconi007's Avatar
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    CnC- refer for sale section. I have for sale the best conical when it comes to low retention.
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  23. #123
    Life-long Learner DesigningByCoffee's Avatar
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    I've just been playing with single dosing the Robur - with a slightly adjusted technique I'm now down to 0g retention. Removed the anti-static screen and guard, weigh and add beans to the hopper - grind all out - sweep the chute clean into a cup - then into the PF. Easy.

    FWIW retention never really bothered me either when I was using it soley for me - but my biggest problem was also using the grinder to grind bags for friends, then adjusting for plunger/other machines etc and back to espresso for me could waste 50-100g getting dialled back in. This allows for an easy transition.
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  24. #124
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    Quote Originally Posted by DesigningByCoffee View Post
    I've just been playing with single dosing the Robur - with a slightly adjusted technique I'm now down to 0g retention. Removed the anti-static screen and guard, weigh and add beans to the hopper - grind all out - sweep the chute clean into a cup - then into the PF. Easy.
    Is that with a Robur-E or the dosered model (I'm using a E model)? You can try RDT (two sprays with a small spray bottle -got mine from Daiso) and it works amazing. Without the spray I need to do multiple pulsing on the grinder to get most ground (99%) out. With spray, no pulsing needed and I get down to 0.0-0.1g 99.5% of the time(after the first pulse). Retains nothing even after a full strip down cleaning -which tells me there's no accumulated grind in the grinder at all.

    Plus it's the most quiet grinder I'v used so far so that's really appreciated. Does seem to need WDT/post mixing the grind for best results. But best grinder I've used so far (for single dosing)!

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    Any issues with popcorning affecting grind size/consistency?

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    To my eye and by measuring the TDS/EY% using a refractometer, I don't think it's an issue (even compared it to a Pharos which doesn't popcorn and well aligned). I've tried running it with a mini hopper for a week. Couldn't notice much difference either in taste or grind consistency, what I did notice was I go through beans significantly faster (cons) and the grinder is even more quiet than it already is (pro) - you almost don't hear it. Ought to run the hopper test again soon.

    It does popcorn so you do need a cover (I use a recycled rubber tamper mat). And you have to adjust the grind setting to a finer range to get the same flow rate - not a negative, just the way how it works.
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  27. #127
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    Is that with a Robur-E or the dosered model (I'm using a E model)? You can try RDT (two sprays with a small spray bottle -got mine from Daiso) and it works amazing. Without the spray I need to do multiple pulsing on the grinder to get most ground (99%) out. With spray, no pulsing needed and I get down to 0.0-0.1g 99.5% of the time(after the first pulse). Retains nothing even after a full strip down cleaning -which tells me there's no accumulated grind in the grinder at all.

    Plus it's the most quiet grinder I'v used so far so that's really appreciated. Does seem to need WDT/post mixing the grind for best results. But best grinder I've used so far (for single dosing)!
    Yeah - Robur-E. A short blast of steam over the beans does the same job if you're careful - or sends them across the room if you're not! I just sweep out, pulse once and sweep again. Gets most out. I'm not overly fussed about a clump or two - few taps to settle & distribute then tamp
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  28. #128
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    I find RDT really interesting. To my eye the grind looks heaps better - not just reduction of static. I am wondering if the addition of moisture also reduces fines.

    When milling grain for beer brewing it's pretty standard practice to add a small amount of water specifically to "Condition" the grain so it does not produce as much dust when it's crushed. I don't know if it's possible that the same Principle can work with coffee.

    One thing I noticed with RDT is I can't swap it in and out without also adjusting the grind. I find if I RDT I need to adjust the grind courser..... This does not suit the theory of less fines.. However, I have another theory that the additional moisture facilitates more compression when tamping.. Therefore requireing a courser grind.

    Anyway.. It's all just speculation. I have nothing to back it up except I prefer using RDT to try and achieve consistency.
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  29. #129
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by Sink_cut View Post
    One thing I noticed with RDT is I can't swap it in and out without also adjusting the grind. I find if I RDT I need to adjust the grind courser..... This does not suit the theory of less fines.. However, I have another theory that the additional moisture facilitates more compression when tamping.. Therefore requireing a courser grind.
    I think you're right. I'm amazed how much finer I need to go compared to a full hopper - so think that compression has something to do with it - but why a few drops of water help? Not sure - maybe like cutting fluid on a milling machine!?

  30. #130
    Senior Member chokkidog's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    You can try RDT (two sprays with a small spray bottle -got mine from Daiso) and it works amazing.
    Aaaah, the good 'ol RDT.

    For them that don't know what the acronym stands for ...take your pick!
    RDT - Definition by AcronymFinder
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  31. #131
    Senior Member Yelta's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    You can try RDT (two sprays with a small spray bottle -got mine from Daiso) and it works amazing. Without the spray I need to do multiple pulsing on the grinder to get most ground (99%) out. With spray, no pulsing needed and I get down to 0.0-0.1g 99.5% of the time(after the first pulse). Retains nothing even after a full strip down cleaning -which tells me there's no accumulated grind in the grinder at all.
    RDT???? Recycling Design & Technologies, roadside drug testing, remote diagnostic technologies or do you mean Rocol rtd cutting lubricant????
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    What these comments are supposed to mean? Sorry for not putting it in full context for those who only hangs around here (my bad) but apparently some just get what I meant. I had mentioned what it inplied as well - apply a bit of moisture to the beans before grinding to reduce static. As usual, if you use mr Google, search for 'RDT coffee' and it basically answers all your questions along with all others that you probably didn't ask.

    Here you go: http://bfy.tw/5v1G
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  33. #133
    Senior Member Yelta's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    What these comments are supposed to mean? Sorry for not putting it in full context for those who only hangs around here (my bad) but apparently some just get what I meant. I had mentioned what it inplied as well - apply a bit of moisture to the beans before grinding to reduce static. As usual, if you use mr Google, search for 'RDT coffee' and it basically answers all your questions along with all others that you probably didn't ask.

    Here you go: Let me google that for you
    Crikey, RDT = Ross droplet technique, how stupid of me not pickin up on that.
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  34. #134
    Senior Member Gavisconi007's Avatar
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    It's also sometimes known as SBT Yelta

  35. #135
    Senior Member Gavisconi007's Avatar
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    Aka Squirty Bottle Technique

  36. #136
    Senior Member flynnaus's Avatar
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    Damn, after spending all that time time consulting chokkidog's link, I was tossing up between Russian Dictionary Tree and Rim Driven Thruster although I must admit I was inexplicably drawn to the University of Alabama's motto: Roll Damn Tide.
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    Quote Originally Posted by Yelta View Post
    Crikey, RDT = Ross droplet technique, how stupid of me not pickin up on that.
    Oh crikey, I guess I have to include an appendices section with dictionaries/Google attached for every post I do now - just so it's fair to everyone
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  38. #138
    Senior Member Yelta's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    Oh crikey, I guess I have to include an appendices section with dictionaries/Google attached for every post I do now - just so it's fair to everyone
    Course you could have said a couple of sprays of water, perhaps not nerdy enough?

    Interesting that none of the 96 entries in Chokkidogs acronym finder mention the Ross droplet technique, pretty obscure I say.

    My favorite is Rim Driven Thruster, the mind boggles.
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  39. #139
    Senior Member Gavisconi007's Avatar
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    I wonder if Matt Perger will do an analysis of the relationship between droplet size, surface tension, and anti-static properties?

  40. #140
    Senior Member Yelta's Avatar
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    Quote Originally Posted by Gavisconi007 View Post
    I wonder if Matt Perger will do an analysis of the relationship between droplet size, surface tension, and anti-static properties?
    Wouldn't surprise me in the least.
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    Doubt he would. Seems a rather pointless exercise.

  42. #142
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    Quote Originally Posted by dlight View Post
    Doubt he would. Seems a rather pointless exercise.
    Ah, that is the point I believe...

    Mal.

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    Strange, I don't find his views pointless, in fact rather insightful.

    But then why are we even debating this.

  44. #144
    Senior Member chokkidog's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    What these comments are supposed to mean? Sorry for not putting it in full context for those who only hangs around here (my bad) but apparently some just get what I meant. I had mentioned what it inplied as well - apply a bit of moisture to the beans before grinding to reduce static. As usual, if you use mr Google, search for 'RDT coffee' and it basically answers all your questions along with all others that you probably didn't ask.

    Here you go: Let me google that for you
    Fair enough Sam...... but to be fair, some who read this forum and all the delights it has to offer, have just stepped off the instant train and

    aren't quite sure where they are.. even more so when we carry on with stuff like:

    The last batch of Yirg, which I roasted in the HG, had a diminishing ROR of 5 -3 between FC and SC and was 7 DPR when

    I tried it in the R58 but I thought the coffee was better when I had it in the GS3 with it's SG, rather than the Rocket's e-61.

    A close third was the BES900, surprising, as it has neither an SG or an e-61. TDS was all over the place but the

    EP's were all identical, with an ER of 1.5 from 20g in a triple. Of course, using an EK43, rather than an SJ, would change EVERYTHING. ;-)

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    Yay CD, don't know if I should laugh,cry, cheer or read some more. Not a complete beginner. I'm onto page three! chippy
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  46. #146
    Senior Member Gavisconi007's Avatar
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    FWIW and IMHO the RDT is just H2O

  47. #147
    Senior Member Vinitasse's Avatar
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    I was more along the lines of WTF and BS

    😜
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  48. #148
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    Yeah that too

  49. #149
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by chokkidog View Post
    Fair enough Sam...... but to be fair, some who read this forum and all the delights it has to offer, have just stepped off the instant train and aren't quite sure where they are.. even more so when we carry on with stuff like:

    The last batch of Yirg, which I roasted in the HG, had a diminishing ROR of 5 -3 between FC and SC and was 7 DPR when
    I tried it in the R58 but I thought the coffee was better when I had it in the GS3 with it's SG, rather than the Rocket's e-61.
    A close third was the BES900, surprising, as it has neither an SG or an e-61. TDS was all over the place but the
    EP's were all identical, with an ER of 1.5 from 20g in a triple. Of course, using an EK43, rather than an SJ, would change EVERYTHING. ;-)

    But you know what is really scary - many of us could follow all of that chokkidog!

  50. #150
    Senior Member Yelta's Avatar
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    Quote Originally Posted by dlight View Post
    But then why are we even debating this.
    Threads evolve, after 170 + posts everything that needs to be said has been said, seems like marathon threads go from, meaningful and on topic > geeky and full of technobabble > lighthearted and frivolous > the end.
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